Have you ever wondered how airplanes navigate in the dark or in the clouds? When you fly back home from your vacation and land into a thick layer of fog, have you ever wondered how the pilots managed to land the airplane? The answer: they fly using only their instruments as references. So, how does this affect you flying your UAV? Well, in short, it means the pilot will not even be looking out his window, so how the heck is he supposed to see your drone?

In the photo below, you will see two rows of round gauges. When flying in bad weather, a pilot will be using these gauges to tell him where he is, and how far he is from other locations. There may also be a couple GPS screens to help navigate, but the pilot must still gather the majority of the information from the round gauges.

Granted, many airliners have flight decks that include more screens and what are called "moving maps," but these are still considered instruments and must still be used in coordination with other instruments to control the airplane.

In order to safely and legally fly like this, pilots are required to have an instrument rating. This advanced rating is commonly known as the most difficult of any license or certification pilots must acquire because of the amount of knowledge and intense training that is required. During training, pilots actually place special goggles on so that they can't see outside. That's right. They are actually prohibited from looking out the window to see anything and they must fly the airplane exclusively using those gauges. They must take off and fly almost the entire flight without looking out the window. In some cases, the pilots can't look outside until they are only 200 feet above the ground, and if the weather is poor enough, all they might see is runway lights! This kind of training is required because, as you can see from the video, real life instrument flying will often require pilots to be flying using their instruments nearly the entire time.

This rating is required anytime an airplane is to fly in or near clouds, fog, or in low visibility conditions. If a pilot is not instrument rated or chooses not to file and fly the flight plan in accordance with Instrument Flight Rules (IFR), he or she must remain in weather conditions that allow them to see out their window a certain distance. Different airspace requires different minimum visibility and cloud clearance, but the most common is 3 miles visibility, 1,000 feet above clouds, or 500 feet below them, or 2,000 feet to the side of them. These distances keep VFR pilots (Visual Flight Rules, or looking out the window and flying using outside references) far enough from clouds that if an airplane flying through them were to suddenly appear, there would be time and distance to allow collision avoidance. However, because the aircraft flying IFR is normally in contact with air traffic control, the presence of the VFR aircraft waiting outside the clouds would probably be relayed to the IFR pilot beforehand, and he may even be vectored further away to avoid potential conflict.

So, this means that if you are NOT flying IFR, you must remain 1,000 feet above, 500 feet below, or 2,000 feet to the side of any cloud, and the overall visibility (due to fog, haze, smoke, etc.) must allow you to see at least 3 miles. If you ARE flying IFR, you can fly into low visibility and clouds. Even in clear conditions, the IFR pilot must be using his instruments to navigate, which means he will spend a majority of his time looking down at his panel. When approaching any cloud or are of low visibility, pilots will normally stop looking outside before they reach the cloud in order to, for back of better terms, get "in the zone" (ie get used to flying on instruments completely) to reduce the possibility of spatial disorientation once entering the clouds. If you take nothing else away from this article, please remember this: Hundreds or even thousands of feet away from a cloud, the pilot will not be looking outside. As has been explained, the pilot will definitely not be looking outside while in the clouds, and will likely remain staring at his panel once out of clouds, at least for a moment or two.

The idea that pilots can see and avoid an UAV while flying in clear air is one that I do not support. (Perhaps, in a best-case scenario, a large Octocopter with flashing strobes against a very contrasted background may be seen by a very sharp-eyed cub pilot flying his airplane very slowly at 50 mph. Hopefully he somehow was warned or knew about the UAV already. Hopefully he is not on a collision course with it already. Hopefully the Octocopter is slightly higher, so it stands out against a pale sky or overcast conditions. Hopefully the UAV is not moving towards the airplane. In this most hopeful situation, there is a chance he would be able to "see and avoid" the UAV... and even that is pushing it.) But the idea that a pilot will ever see a UAV while in or near clouds? Not going to happen.

There are a number of other arguments that can be made as well:

An electrically driven UAV flying into a cloud or layer of fog that is made of water... think about it.

Flying a UAV beyond line of sight (ie into a cloud or fog) means you actually don't know where it is. Even if you have a map that shows it's location, In the US, this kind of flying is not legal. Even where it is legal, it is a bad idea.

This technology is new. It has glitches, and fly-aways do occur. The software might glitch, and the the hardware might as well. One faulty motor and the UAV could end up flying out of control. If you can't see the UAV, then you might not know what is happening at all. Even if you can see your FPV screen, all you will see is white/gray, so you will have no idea if you are spinning out of control or not.

Temperature in the clouds may be vastly different from where you are. Some UAVs have operating temperature limitations. The reason clouds form is because moist air reaches a level of pressure in the atmosphere below which the water vapor held in the air will condense due to over-saturation. By definition, there will be a lower temperature in the clouds. This drop in temperature may significantly decrease battery power. In some cases, ice build up may be possible, freezing up the motors or spoiling the aerodynamic properties of the propellors. However, it is likely that water would short out the electronics before this happened.

If you choose to fly above a thin layer of fog or cloud, not only will it be difficult or impossible to determine the location of the UAV, it may be incredibly difficult to judge your speed and you may fly right out of radio range without knowing it.

Further learning about Instrument Flying is encouraged and can be found here: